I'm working on an ESD clamp. The clamp is triggered by both, fast rising voltage and voltages above a threshold. I use a diode array for triggering with high voltages, but the temperature dependence shifts the trigger voltage, At 25 °C I have 4.2 V as desired, at 100°C I'm aready triggering at 3.5V. At -40°C I trigger at 5V which is too high. Any ideas on how to compensate for the temperature variation?